If $3.365 \text{ g}$ of ethanol $(l)$ is burnt completely in a bomb calorimeter at $298.15 \text{ K}$, the heat produced is $99.472 \text{ kJ}$. The $|\Delta H_f^\circ|$ of ethanol at $298.15 \text{ K}$ is . . . . . . $\times 10^2 \text{ kJ mol}^{-1}$.

Fill in the blanks:
$(i)$ The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states is called the ...... of that compound.
$(ii)$ The total heat change in a chemical reaction is equal to the algebraic sum of the heat changes of the individual steps of the reaction. This law was given by ............. .
$(iii)$ $A$ process during which there is no exchange of heat between the system and the surroundings is called an ................ process.
$(iv)$ The standard enthalpy value of any element in its standard state is considered to be ...... .

What will be the $C-H$ bond enthalpy if:
$CH_{4(g)} + 2O_{2(g)} \rightarrow CO_{2(g)} + 2H_2O_{(l)};$ $\Delta H = -890 \, kJ$
$CO_{2(g)} \rightarrow C_{(graphite)} + O_{2(g)};$ $\Delta H = 393 \, kJ$
$2H_2O_{(l)} \rightarrow 2H_{2(g)} + O_{2(g)};$ $\Delta H = 571 \, kJ$
$2H_{2(g)} \rightarrow 4H_{(g)};$ $\Delta H = 871 \, kJ$
$C_{(graphite)} \rightarrow C_{(g)};$ $\Delta H = 716 \, kJ$

Which of the following equations represents the standard enthalpy of formation of $CH_4$?

Given that,$C_{(s)} + O_{2(g)} \longrightarrow CO_{2(g)} ; \Delta H^{\circ} = -x \ kJ \ mol^{-1}$ and $2CO_{(g)} + O_{2(g)} \longrightarrow 2CO_{2(g)} ; \Delta H^{\circ} = -y \ kJ \ mol^{-1}$. The enthalpy of formation of $CO$ will be:

The $\Delta H_f^o$ for $CO_{2(g)}$,$CO_{(g)}$ and $H_2O_{(g)}$ are $-393.5$,$-110.5$ and $-241.8 \ kJ \ mol^{-1}$ respectively. The standard enthalpy change (in $kJ$) for the reaction $CO_{2(g)} + H_{2(g)} \to CO_{(g)} + H_2O_{(g)}$ is